A quite common container closure is referred to as a "crown" closure, by reason of its analogous appearance to the tiara or crown of royalty, being of frusto-conical shape and having a metal or plastic closure member with a top panel, a skirt depending from the top panel with exterior undulated surface and interior sealing means adapted for sealing engagement with the upper surface of the neck of a container.
The merits of such crown closures, and other related closures of simple structure such as straight skirt line closures which are essentially cylindrical in shape, are dependent largely upon their ability to maintain container pressurization existing at the time of their initial application to the container, and to withstand increased internal pressures in the container which, if in excess of the sealing retention capability of the closure, can give rise to leakage of pressurization of contained contents or actual liftoff.
Based on events of tampering over the past decade, giving rise to deaths of consumers, a further desired characteristic of crown and related simple closures is the facility for tamper indication. The prior art indicates various versions of the relatively complex structure of so-called "tamper-evident" closures of type leaving a telltale band separable from the closure upon the container in the course of initial opening thereof, and the somewhat simpler, see-through and closure member-activated, tine-type tamper-evident closure of various co-pending patent applications of applicants.
From applicants' viewpoint, presently known crown closures do exhibit levels of sealing of desired magnitude. However, being of metal, they are prone to rust and present an exterior with sharp edges, which can cut the hands. Also, they are not tamper-evident and can be removed and replaced without evidencing the same. A crimping operation is needed in initial application to a container to effect sealing.
Certain synthetic molded bottle closures are known which have internal beads cooperative with circumferential indentations on bottle necks. The greater the radially interior extent of such bead, the greater is the capacity for pressure retention. However, in the case of synthetic molded closures, the radially interior extent of such beads has been limited such that the molded closure may be removed or stripped from its forming core without damage to the bead and without need for collapsible forming cores, use of which entails increased expense and complexity in the making apparatus. It is clearly desirable to provide practice and structure which can increase the radially interior extent of sealing beads to thereby maximize sealing and pressure retention capability.
As above alluded to, tamper indication facility in simple closures is desirable. Heretofore known crown and related closures of simple construction do not exhibit such facility.